“The mind comes to know things by comparison” one effect being “that knowledge derived from acts of comparison acquires characteristics of its own” (Strathern 2020, 29). For instance, without having a distinct idea of what a “woman” is, we gain a pretty clear idea of what a “sister” is when we compare two women “in reference to one common parent“ (ibid, 30). Thus, “to have a clear conception of that which is the foundation of the relation… may be done without having a perfect and clear idea of the thing it is attributed to” (Locke in Strathern 2020, 30).